Antipsychotics (APs) are frequently prescribed for the management of behavioural and psychological symptoms of dementia (BPSD). However, three safety warnings have been issued (2002, 2004 and 2005) due to an increased risk of cerebrovascular event and mortality.
The aim of this thesis was to evaluate AP usage in the population of community-dwelling elderly with dementia, and to determine the effect of safety warnings on usage patterns.
A retrospective cohort of 10,969 elderly with dementia who initiated an AP treatment between January 1st, 2000 and December 31st, 2009 was identified through in the databases of Régie de l’assurance maladie du Québec (RAMQ). Segmented time series analysis was used to quantify the effect of safety warnings on AP dispensing rate. The effect of the 2005 warning on the characteristics of treated patients and on usage patterns (dose and duration) was evaluated, respectively through multivariate logistic and multiple linear regression models.
Atypical AP dispensing rates increased until the 2005 safety warning and decreased by 8.96% (95% CI: -11.91% – -6.02%) thereafter. Analysis by individual products yielded similar trends for risperidone, the only AP approved in Canada for elderly with dementia. However, usage of quetiapine, which is off-label, kept increasing. For all products, rate of treatment initiation decreased over time. Safety warnings did not seem to be associated with either changes in prescribed treatment dosage or duration, nor with prescription channeling toward lower risk patients. Apparent lack of efficacy of safety warnings is likely due, in part, to absence of effective treatment alternatives for BPSD.